1. Field of the Invention
The present invention relates to a bag of the type which is carried on the back of a user by being suspended from the shoulders of the user, particularly to those known as a knapsack, rucksack or back pack.
2. Description of the Related Art
In general, a back bag such as a knapsack or a back pack has a pair of shoulder straps by which the bag is suspended from the user's shoulders so as to be carried on the user's back. The back bag, particularly when it is designed for use in mountain climbing or hiking, has a bag portion of a comparatively large internal volume to contain many articles which heavily burdens the user for many hours during a long-distance walk or ascending or descending steep slopes. It is, therefore, desirable that the heavy load is uniformly distributed over the entire area of the user's body, particularly his shoulders, back and waist, and that such a uniform distribution is maintained during movement of the user's body.
To cope with such a demand, back bags have been proposed on which a hip belt is provided in addition to a pair of shoulder straps, as disclosed in Japanese Utility Model Laid-Open Nos. 55-89322 and 56-27029 and Japanese Patent Laid-Open No. 61-247409. The hip belt is adapted to be fastened around the user's hip bone, on which the load of the articles is stably borne.
These conventional back bags, however, are designed and constructed such that the hip belt is integrally fixed on the bag portion by sewing or other means. Thus, there still exists a problem that the hip belt cannot be worn around his hip bone in sufficient conformity with the user's physical shape.